1. Field of the Invention
The present invention is directed to a radiation diaphragm for an X-ray apparatus of the type having a variable-position absorber element for adjustably limiting a ray bundle. The invention is also directed to an X-ray apparatus employing such a radiation diaphragm.
2. Description of the Prior Art
Radiation diaphragms for X-ray apparatuses are disclosed, for example, by German PS 42 42 835, German PS 42 29 321 and European Application 0 103 794. As absorber elements or diaphragm jaws, the radiation diaphragms of German OS 42 29 312 and European Application 0 103 794 have at least two diaphragm plates that are linearly adjustable relative to one another in pairs, a ray bundle having a rectangular cross-section of different sizes being able to be gated thereby. European Application 0 103 794 additionally discloses pivotable, triangular diaphragm plates that also allow the gating of a ray bundle having an approximately circular cross-section. To this end, the additional diaphragm plates are respectively pivoted around an axis that proceeds parallel to the middle axis of the ray bundle.
A computed tomography apparatus having a radiation diaphragm is disclosed in German OS 44 37 969. An X-ray fan beam is generated by the primary radiation diaphragm fashioned as slit a slot diaphragm. This fan beam determines the dose profile in the patient, and thus the slice thickness in the exposure. It thus also influences the dose stress on the patient and the intensity of the detector signal from which the image data are acquired. It is necessary to set different apertures of the primary radiation diaphragm for setting different slice thicknesses.